Disposable containers containing cold or hot liquids are in wide use. In order to prevent the liquid from being accidently spilled during use, it is known to cover the open upper end of the container with a disposable cap having an upwardly extending drinking spout. The cap has a peripheral socket which engages the periphery of the upper end of the container.
Known caps when secured to such containers are subject to substantial and undesired leakage when a container of liquid covered with a known cap is disposed horizontally on its side or even when the container is disposed vertically and is subjected to sudden movement as for example when held in a moving vehicle so that the liquid surges upward and out ot the spout.
The present invention is directed toward a new type of disposable cap which eliminates such liquid leakage problems.